Garden tips: going underground

What is it about fertilizer that plants know and people never ponder? We commonly think that if a plant is planted in the soil then it will thrive and grow to its ultimate ideal mature size and flowering or fruiting ability.

Often this is not the case, and frequently the plants we cultivate don’t thrive at all. In the past, bringing in a cartload of steer manure, some chicken poop, and a bucket of egg shells would make for a good garden. Granted the smell was pretty bad for a couple of weeks but the tomatoes would be worth it. Some just buried a fish under each plant and that would do the trick. Now we have boxes and bags of pelletized organic fertilizer. We have synthetic granules that have coatings of polymer lasting up to three months slowly releasing the fertilizer into the soil whenever watered. We also have liquid fertilizers that come in myriad formulas you mix in a watering can or dilute from a concentrate. These fertilizers access the roots of plants quickly and thoroughly, feeding immediately and giving results for two weeks. They can create a spectacular bloom show in a flower bed.

There are problems with fertilizers, however, and using them incorrectly may cause damage to your garden or runoff downstream. What I’m going to attempt to cover in this column is how to use fertilizers in your garden.

1. Different plants prefer different fertilizers. Know your plants, and then you can learn the foods that work best for them. Take photos of the whole plant, some leaves and a flower or two and then bring the photos and a sample leaf to a nursery and ask for identification.

2. While at the nursery, ask what fertilizer they recommend for that type of plant and write down the brand name of the fertilizer and the three numbers found on the package. For example, 5-1-1 is blood meal, 15-30-15 is one of several different types of the Miracle Grow brand. 3. Look up your plant on the Internet or in your plant encyclopedia. The Sunset Western Garden Book is a good encyclopedia to get. Once you have a pretty good idea about your plant fertilizer needs, compare that information with the information you got from the fertilizer package.

4. The numbers you saw on the fertilizer package at the nursery are the percentages of nitrogen, phosphorus and potash. Nitrogen stimulates green growth, phosphorus stimulates bloom, and potash stimulates root growth and plant vigor. These, in correct proportions for your plants, make for ideal growing, flowering and fruit or vegetable production.

5. Some plants like more acid in their soil. This can be achieved with fertilizers. Camellias, rhododendrons, azaleas and hydrangeas are just a few types of plants that like a lower pH in their soil (higher acid level). This does not mean that giving your plants coffee grounds or vinegar will be a good thing. You can too easily overdo the acid. Look up the correct types of fertilizers, go to several nurseries and ask for help. You will find dozens of fertilizers and easily become overwhelmed. Take in the information and make your decisions at home. Write everything down.

6. Take before-and-after color photos of your plants. That is, before fertilizing and again two weeks later. You may think you’ll remember what the plant looked like, but a photo taken in the same light, the same time of day two weeks apart should show you if your fertilizer program is working.

7. Read all the instructions on any packages of fertilizer and the proportions to use for different sized plants. Read about all the types of plants this fertilizer is good for. Look for warning labels. Follow the instructions as written and don’t use more than is advised.

8. If you get fertilizers without any instructions, ask the person selling them or giving them to you for the proper proportions to apply to your plants. Try to get a list of ingredients and look them up so you’ll know their benefits. Some plants will take longer to respond to fertilizers. This is especially important for organic fertilizers. If a person sells or gives you a bag of chicken litter with manure or a bucket of fish guts, it’s important to know what they recommend the proportions are to put around your plants. More is not necessarily better when it comes to fertilizer.

9. Do not put piles of fertilizer around your plants. Spread the fertilizer evenly over the root zone, not around the trunk. What is the root zone? It is the area from the drip line (straight down from the outside of the leaves) to about a foot or more from the trunk. A tree will obviously have a greater drip line than a camellia bush and a plant like a tomato even less. Always water in your fertilizer. No matter what kind you use, the only way it can get to the roots is if you water it in. Think about how deep your roots are and how deep you have to water to get it down to where most of them are. Most plants have a root surface equal to the canopy surface. Most roots (even on trees) are only 18 inches deep.

10. The difference between organic fertilizers and synthetic or chemical fertilizers is the concentration of nitrogen, phosphorus and potash. Organic fertilizers have lower concentrations and often more micronutrients. It’s important to know this because if you apply synthetic fertilizers in the same proportion as organic fertilizers, you may burn your plants. Organic fertilizers are most often used on vegetables, fruits and edible plants. Often they can contribute to good fungi and bacteria growth in the soil which is good for plants. They do less harm to worms and microorganisms, they add a natural aesthetic to plant cultivation that one does not get from a bag of chemistry.

Jack McKinnon is a garden coach. He worked in the Sunset Magazine Gardens for 12 years and can be reached at 650-455-0687 or email at Jack.Mckinnon.hmb@gmail.com.